JPH1039623A - Flexible doctor blade - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide improved toner measuring ability. SOLUTION: A flexible doctor blade has a backing layer of resin film and also a flexible laminate 3 which carries binder which contains abrasive particle such as silicon carbide particle and the like and a conductive means is included. As the conductive means in a preferred embodiment, conductive carbon black contained in the resin film which contains silicon carbide for polishing is provided. This flexible laminate 3 is supported on an aluminum bar 1. A flexible foam layer 2 is fixed on a bottom side of the bar and a shim 10 is included on a lower side of the flexible foam layer 2. The shim 10 has hardness of about 0.5-31.0 inches (flexibility)/inch(length)/pound(force). The laminate 3 is bent to the foam layer and downward of the shim and contacted with a developing roller 6. The conductive layer keeps its conductivity when it is abrasive while used. The doctor blade may reduce the toner stored in a prenip area and the toner is effective to the developing roller 6 and also enable uniformed measurement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a component used in a toner cartridge for electrophotography, and more particularly, to transfer toner to a photoconductive surface carrying a latent image to be developed by toner. And a flexible doctor blade for assisting transfer of toner to a developing roller.

[0002]

2. Description of the Related Art Commercially available laser printers charge a toner and bring the toner into contact with the surface of a rotating developing roller so that the developing roller nips into contact with a drum-shaped photoconductor having a photoconductive surface. Electrophotography is often used to carry a metered amount of toner to be measured. The developing roller is semiconductive and is charged to a potential between the potential on the toner and the potential of the charged area of the photoconductor. When the developing roller rotates, the toner is sucked from the toner supply source to the developing roller.

A doctor blade (adjusting blade) that comes into direct contact with the surface of the developing roller when the developing roller is rotated so as to be brought into nip contact with the surface of the photoconductor while the surface of the developing roller is in contact with the toner supply source. The doctor blade is charged to a potential of the same polarity as that required for toner passing below the doctor blade. The function of the doctor blade is to provide a controlled or regulated thin layer of toner on the developer roller. These doctor blades, combined with developer rollers, are known as "Doctor Blade Design for Monocomponent N".
onmagetic Developer) "" (IBM Technical Disclosure
Bulletin, Vol. 33, No. 5, October 1990, 14-
15). The blade described in that article is slightly roughened on the surface in contact with the developing roller. A significant portion of the toner carried to the blade is charged with a polarity opposite to that intended for the developer. The interaction of the blade, charged to the intended polarity, with the mechanical effects of contact between the blade and the developer roller results in a very significant intended charge state of the toner passing through the blade.

Therefore, the purpose of the doctor blade is
It consists of (1) uniform metering of a thin layer of toner on the surface of the developing roller during rotation, and (2) assisting in uniform charging of the toner on the surface of the developing roller. Properties such as surface roughness, nip force, electrical continuity, and abrasion resistance are important for proper functioning of the doctor blade. However, the above-described doctor blade is rigid along its length, and therefore responds to surface variations in the doctor blade itself and, depending on surface variations in the developing roller with which the doctor blade comes into contact, Provide a toner layer having a variable thickness. Such variations in the toner layer cause corresponding variations in the visible image formed by the printer. This results in a pattern such as a horizontal line and a horizontal band, which is a serious print quality defect. Therefore, a more strongly desired characteristic for the doctor blade is the flexibility (of the blade) in the toner adjustment nip as the nip where the toner adjustment is performed, and this flexibility is applied to the irregular surface of the developing roller. This allows the blade to be more fully adapted. This adaptability creates a uniform pressure in the toner adjustment nip, making the charge and fluidity of the toner more uniform. This results in improved print quality when forming gray scale (achromatic scale) images.

[0005] Such a flexible doctor blade,
U.S. Pat. No. 5,085,171 to Aurick et al. (1) for a flexible doctor blade having a thin metallic outer layer on a flexible backing having a grit surface in contact with a developing roller.
Published February 4, 992). This thin metal layer provides electrical conductivity to the blade. This blade conforms more closely to the surface of the developer roller to be contacted by being more flexible than the rigid one in the prior art doctor blades described above, thereby making it more uniform on the developer roller. It provides a good toner layer. However, although the doctor blade has been used successfully, the outer metal layer provides the necessary electrical path to charge the doctor blade where it contacts the developer roller, so that the outer The wear of the metal layer limits the useful life of the doctor blade. There are other problems arising from the flexibility of the blade in use. Particularly when this blade is used, the force of the abrasive paper-like layer on the foam (foam) layer (on the back of the abrasive paper-like layer) causes the conductive abrasive paper-like material to expand due to the flexibility of the foam. The nip of the object-developing roller is extended and curved.
This is in sharp contrast to the nip formed between the steel doctor blade and the developing roller. In that case, the inflexibility of steel makes it impossible to adapt to the developing roller and remains flat in the nip area, providing a short flat nip. The end result of such deformation in the pre-nip region (pre-nip region) and in the nip region is a high or low toner flow that is effervescent. Such fugitive toner flow rates will produce light and dark areas when printing grayscale and black.

Another example of a flexible doctor blade design is the "Extended Life Flexible Doctor Blade (" Ext
ended Life Compliant Doctor Blade ")"
No. 08 / 524,275 to Bracken et al. (Filed September 6, 1995). This structure is based on the above Au
The doctor blade of lick etc. is modified in the following two points: (1) The layer that comes into contact with the developing roller is not a thin metal layer on the grit surface in Aullick etc. (2) the support member of the blade extends the full height of the blade to provide some stiffness, and the grit / conductive material around the stiffness provided. The layer is bent to contact the developer roller (thus minimizing foam compression at the nip corners and toner accumulation at that point). However, while this structure eliminates the tunnel-like pre-nip region, it does not alter the long radius curved nip or the problematic results of the above-mentioned high and low toner flow rates with drifting properties.

[0007]

Thus, a flexible doctor blade that is effective over time and adapts along the length of the developing roller, but is non-flexible to provide optimal toner flow and printing characteristics. There is a strong need for a flexible doctor blade that provides a pre-nip and nip configuration similar to that provided by a doctor blade.

[0008]

SUMMARY OF THE INVENTION The present invention is an electrically-excited doctor blade which physically contacts a sector of a developing roller with the surface of the charged doctor blade. It is an object of the present invention to provide an electrically excited doctor blade for measuring a charged electrophotographic toner held on a developing roller. The doctor blade includes a flexible backing member, a supporting member for positioning the blade adjacent to the developing roller, a flexible foam layer bonded to a side of the supporting member facing the developing roller, About 0.5 to about 31.0 inches (flex) / tied to the side of the foam layer facing the developer roller.
A shim having a rigidity of inch (length) / pound (force), a layer provided on the flexible backing member, the layer including a conductive means and a solid binder in which grit particles are completely dispersed; The backing member, the conductive means, and the layer having a grit are bound to the support member and can be bent to extend below the foam layer and the shim; Is configured to contact the sector of the developing roller in operation.

The shim is any material that exhibits flexibility in a direction perpendicular or perpendicular to the process direction, while the shim is made to prevent deformation of the elastic foam layer in the pre-nip region. It can be made of any material having sufficient rigidity in the direction, thereby accommodating the doctor blade in close contact with the surface of the developing roller. Examples of materials used for shim fabrication include polyester and stainless steel.

[0010]

DETAILED DESCRIPTION OF THE INVENTION One design example of an improved flexible doctor blade is described herein, which has the desired flexibility for the developing roller, but has a funnel-shaped pre-nip or Long, as found in flexible doctor blades already known in the art,
Does not include rounded nip area. The improved doctor blade does not reveal the problem of the high and low toner flowability of the prior art flexible doctor blade. In the present invention, a flake as a shim (gap adjusting plate) is bonded to the bottom surface of the elastic foam (foam) layer, and is present between the foam layer and the conductive abrasive paper in contact with the developing roller during operation. The rigidity of this metal shim in the process direction prevents the foam from deforming in the pre-nip region into an undesirable funnel shape. The prenip area of the present invention is approximately equivalent to that found on steel doctor blades. Also, the stiffness of the metal shim prevents undesirable long and rounded nip shapes and mimics the nip shape of a steel doctor blade. The overall flexibility of the blade is maintained because the stiffness provided by the shim is only effective in the process direction and not along the length of the developer roller.

As shown in FIGS. 1 and 2, the flexible doctor blade according to the present invention preferably comprises, for example,
An aluminum support bar 1 which is a stock bar (length: 231.5 mm) of aluminum 6063-T5 of 4.0 mm × 10 mm is provided. Extending the length of the bar 1 is a laminate 3 comprising a flexible backing member, which is provided on its outer surface (i.e., the surface in contact with the developing roller) in a binder. Carrying conductive means with a solid binder having dispersed grit particles. In a preferred embodiment, the flexible backing is a substrate comprising a film of polyethylene terephthalate polyester resin having a thickness of about 0.002 to about 0.005 inches (ie, about 0.051 to about 0.127 mm). . Other materials that can be used for such a flexible backing member include polyimide and paper. The solid binder supported on the flexible backing member is, in a preferred embodiment, a cured polyurethane having grit particles completely dispersed therein (eg, Lord Ched).
Z001) available from Mical Corp. The grit particles typically have a particle size of about 8 μm to about 20 μm in diameter, preferably about 13 μm to about 16 μm, and are preferably such as silicon carbide (commercially available from Norton Corp.). Ceramic oxide. Other grit particles useful in the present invention include aluminum oxide,
Diamond powder, titanium dioxide, zirconium dioxide,
As well as mixtures thereof.

The flexible backing member also comprises conductive means. The conductive means effectively obtains the current applied to the doctor blade and conducts it to the developing roller. Examples of such conductive means that can be used in the present invention include those disclosed in US Pat. No. 5,085,171 to Aulic et al., Issued Feb. 4, 1992, which is incorporated herein by reference. There is a metal layer. A preferred conductive means used in the present invention is one in which conductive particles are contained in a solid binder carried by a flexible backing member and dispersed in the binder. Conductive materials that can be used in the present invention include carbon black, graphite, metal fillers, ionic salts, and mixtures thereof. A preferred conductive material is carbon black.
The conductive particles contained in the solid binder are about 2 × 10
It should be provided as a layer having an electrical resistance of less than 5 ohm / sq cm.

The laminate 3 is held on the bar 1 by an adhesive which is strong enough to withstand the forces acting on the laminate. An example of such an adhesive is a commercially available double-sided adhesive tape 5 made of 1 mil (0.0254 mm) thick polyester with adhesive on both sides, the total thickness of which is 0.13 mm, width Is 8.5 mm, which is the same length as the bar 1.

The developing roller 6 includes a semiconductive organic elastomer charged to a predetermined potential by a fixed potential source.
When the developing roller 6 is rotating clockwise, it is in contact with the supply source of the charged toner. Although a considerable amount of toner is charged to a polarity opposite to that of the developing roller 6, usually, the toner is mainly charged to the same polarity as that of the developing roller 6.
Such a toner is carried in a region (sector) of the developing roller 6 facing the doctor blade 1, and the toner of the opposite polarity is blocked by the charged doctor blade, and only a thin layer of the toner passes under the doctor blade. This thin layer is, for the most part, charged to the correct polarity.

A thin conductive band 4 (preferably about 8 mm
Width) straddles bar 1. The band or strip 4 is preferably an 18 mm long piece of commercially available copper subbing tape, and a conductive adhesive surface tied to the laminate 3 across the top of the bar 1, Has an opposite conductive adhesive surface bonded to the opposite bar 1. This band makes electrical contact between the laminate 3 and the bar 1. Laminate 3 is passed through band 4
The roller 6 is charged to the same polarity as the roller 6 by a fixed potential source that contacts the back of the band 4. As an alternative to band 4, simply punch a hole in laminate 3 to form
Filling the hole as an electrical contact with a conductive adhesive such as silicone or epoxy adhesive which is subsequently cured and solidified.

In the preferred embodiment, the conductive band between bar 1 and laminate 3 is about 50 Shore A when dry.
A flexible elastomer having a hardness of less than about 70% to about 96% (preferably from about 94% to about 96%) having a hardness of less than about 70% (vulcanizable silicone or latex rubber at room temperature); In a range of about 4% to about 30% (preferably, about 4% to about 6%). The paste can optionally also contain a common solvent such as methyl ethyl ketone. The composition of these pastes is "Electrical Contact Material For Flexibl"
e Doctor Blade ", which is described in detail in a U.S. application to Bracken et al.

Disposed on the bottom surface of the support bar 1 (ie, the surface of the support bar facing the developing roller) is typically an elastic foam (foam) having a thickness of about 2 mm to about 3 mm. And is provided over the entire length of the support bar 1 in the length direction. This elastic foam layer 2 is attached to the lower side of the support bar 1 using a usual adhesive. The adhesive withstands the forces acting on it during operation of the doctor blade, and is preferably a commercial double-sided tape of 1 mil (0.0254 mm) thick polyester with adhesive on both sides. The preferred foam material for use in the present invention is a polyurethane foam, Poron foam, commercially available from Rogers Corp.

An important feature of the present invention is that a shim (or gap adjusting plate) 10 is attached to the bottom surface of the elastic foam layer (that is, the surface of the elastic foam layer facing the developing roller 6). In selecting a shim 10, it is important to maintain an appropriate balance between stiffness and flexibility (or flexibility). In particular, the shim 10 is in the process direction (ie,
It is necessary to maintain rigidity in the direction in which the developing roller 6 moves (moving direction) and flexibility in a direction perpendicular to the process direction (that is, the length direction of the doctor blade 6). The flexibility along the length of the doctor blade allows the doctor blade to conform closely to the surface of the developing roller 6, while providing the proper nip configuration and the rigidity of the shim. Thus, the doctor blade according to the invention offers the advantages of both a non-flexible steel doctor blade and a flexible doctor blade. Any material that maintains this proper balance of flexibility and rigidity can be used as the shim of the present invention. Both the nature and thickness of a particular material are important in determining whether a particular material is suitable for use as a shim. In particular, if the material is too thin, the required appropriate degree of rigidity is not obtained, while if the material is too thick, the required degree of flexibility is not exhibited. The shim can be made of any material that has the required trade-off between flexibility and rigidity,
Preferably, it does not corrode and has a reasonable cost. Examples of materials used include brass, phosphor bronze, beryllium copper, polycarbonate, polyester, stainless steel. Polyester is a particularly preferred material because it is easier to cut into the desired shape than metal.
Stainless steel is also a preferred material due to its attractive cost and the fact that it does not corrode.

As an example, if stainless steel is used to make the shim, it may be about 0.004 inches (0.102 m).
At thicknesses less than m), the shim becomes too brittle. When using polyester (eg, Mylar, commercially available from Dupont), material thicknesses less than about 0.014 inches (0.356 mm) are too flexible,
Greater rigidity is required. On the other hand, stainless steel with a thickness of more than about 0.012 inches (0.305 mm)
It is too thick to provide the required degree of flexibility. The thickness of the shim material so selected is simply a function of the trade-off between required stiffness and flexibility. The shim material used in the doctor blade of the present invention is about 0.5 to about 31.0, preferably about 10.0 to about 25.0 (unit:
It must have a stiffness of inches (deflection) / inch (length) / pounds (force). This stiffness is measured as follows. One end of a 4 mm wide shim is fixed and a load is applied to the other end (the magnitude of the load should be small enough so that the shim does not plastically deform), and then the displacement of the load end is measured. In another example, the stiffness of the shim should be greater than the stiffness of 0.014 inch (0.356 mm) thick polyester and less than or equal to the stiffness of 0.012 inch (0.305 mm) thick stainless steel.

The position of the shim 10 on the elastic foam layer 2 is important. In particular, the shim 10 should be aligned with the leading edge 9 of the doctor blade 6 (ie, the edge of the doctor blade where the developing roller first encounters in use).
This shim 10 needs to extend the entire length of the doctor blade. The shim 10 is fixed on the elastic foam layer 2 using an adhesive that hardens and hardens over time. What is important is that the adhesive can prevent deformation and displacement of the shim 10 during use.
This is particularly important since the shim will be under constant shear stress during use. Examples of useful adhesives include acrylic adhesives. Acrylic adhesive (for example, # 9469 double-sided tape commercially available from 3M)
Preferably, the shim is fixed to the elastic foam layer 2 using The shim 10 need not cover the entire bottom surface of the elastic foam layer 2 as long as the shim 10 is aligned with the leading edge 9 of the elastic foam layer 2. However, it is preferable that the shim is dimensioned and arranged so as to cover the entire bottom surface of the elastic foam layer 2 in order to considerably facilitate the assembly and adjustment of the doctor blade.

In one embodiment, the doctor blade of the present invention is formed by extending a part of the support bar 1 along the elastic foam layer 2 so as to end (end) at a position aligned with the shim 10. Well, this allows the support bar 1
At the base of the extension, the laminate 3 is forced to roll substantially directly towards the nip area, so that the size of the wedge area between the doctor blade and the developing roller 6 where toner can accumulate is reduced. . This type of construction is described in U.S. patent application Ser. No. 08 / 524,275, filed Sep. 6, 1995 by Bracken et al., Entitled "Extended Life Compliant Doctor Blade."
Doctor Blade ")".

The elastic foam layer 2 can be made of any commercially available foam (foam) having an appropriate elasticity. Preferably, the foam 2 is a commercially available polyurethane foam having a density of about 20 pounds per cubic foot (0.32 g / cm3). This form 2 is approximately 4 mm wide and 0.013
It is held in place by a double-sided adhesive tape with a thickness of mm. Various alternatives to Form 2 can be readily utilized. In use, when the laminate on the flexible backing member 3 is folded back as described above, the inherent elasticity of the foam material and the backing member provides the laminate 3 with a force toward the developing roller 6.

A slurry of a complete mixture of silicon carbide grit, conductive carbon black, and a polyurethane-based adhesive is applied to a thin layer coating (eg, about 25
μm to about 35 μm)
About 0.005 inches (i.e., from about 0.051 mm to about 0.25 mm).
A preferable laminate 3 is formed by applying and curing a resin substrate (that is, a flexible backing member) having a thickness of 127 mm). This slurry is hardened,
Forming a conductive layer; Conductivity is imparted by carbon black. Type XE-2 carbon black, a product of Degussa, is preferred for use in the present invention. With a carbon black content of about 5% by volume in the slurry, a peak response in electrical properties is obtained, resulting in less than about 2 × 10 5 ohms / cm 2, preferably about 1
The electrical resistance is less than × 10 5 ohm / square cm. A carbon black content greater than about 5% by weight results in a surface roughness that is too smooth to properly meter the toner, regardless of the particle size of the abrasive particles used.

There is a peak response in the tuning performance using abrasive particles in the diameter range of 13 μm to 16 μm. This grit size gives an average roughness (Ra) of 0.9 μm to 1.1 μm. If the diameter is smaller than 13 μm, the surface is too smooth and the excess toner is metered under the doctor blade. If the diameter is larger than 16 μm, the surface is too rough, and the amount of the toner under the doctor blade is measured. Also, the larger the particle size, the sharper the surface will be, which will scrape off a large amount of toner from a small area on the surface of the developer roll, resulting in streaks perpendicular to the printed page surface. Any type of ceramic oxide grit can be used in the present invention. Examples of such materials include silicon carbide, aluminum oxide, having the particle size ranges specified herein,
Includes diamond powder, zirconium dioxide, as well as titanium dioxide. Although the conductive / grit laminate wears away from the flexible backing, the electrical properties of the doctor blade remain unchanged because it is conductive throughout.

FIG. 2 shows an embodiment in which the doctor blade of the present invention is used. In use, the laminate 3 is flexible, and is simply bent rearward at a position adjacent thereto with the rotation of the developing roller 6. The flexible backing member 3 and the elastic foam layer 2 provide a force to hold the conductive / grit laminate against the developing roller 6. The stiffness of the shim 10 in the direction in which the developing roller 6 rotates prevents deformation of the leading edge 9 of the elastic foam layer 2, thereby providing a pre-nip region having the best shape 8. This pre-nip area is approximately equivalent to that found on steel doctor blades. Also,
The stiffness of the shim mimics a short, flat nip shape 7 with steel blades, rather than an undesirable long, rounded nip shape. The stiffness provided by the shim is effective only in the process direction and not along the length of the doctor blade (i.e., the length of the developing roller 6), thereby maintaining the overall flexibility of the doctor blade. This is due to the narrow or narrow width of the doctor blade (preferably about 4 mm), the width of the nip (i.e., about 0.5 mm to about 1.5 mm, preferably about 1 mm).
mm), as well as the overall length of the doctor blade (approximately 230
mm to about 233 mm, preferably about 231.5 mm). The preferred thickness of the shim is about 0.014
Inches (0.356 mm). A preferred material for the shim is polyester.

Various changes in the forms and materials used are readily apparent to those skilled in the art, and such changes will be within the scope of the present invention. The scope is sought as specified by law, particularly with reference to the claims.

[Brief description of the drawings]

FIG. 1 is a perspective view of a doctor blade according to the present invention.

FIG. 2 is a cross-sectional view of the doctor blade shown with the developing roller in operation, taken along line 2-2 of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Support bar 2 Foam layer 3 Laminate (backing member) 4 Conductive band 5 Double-sided adhesive tape 6 Developing roller 7 Nip 8 Prenip area 9 Front edge of foam layer 10 Shim

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Jeffrey Earl Brenner United States 40515 Kentucky, Lexington, Eagle Creek Drive 183 (72) Inventor Martin Vu Digiloramo United States 40504 Kentucky, Lexington, Della Drive 873 (72) Inventor Sam E. Murinix Jr. United States 40503 Kentucky, Lexington, Clays Mill Road 1929 (72) Inventor Donald W. Stafford United States 40502 Kentucky, Lexington, Sinoe Road 542 (72) Inventor Peter・ E Wallin United States 40515 Kentucky, Lexington, What Doo Water drive 4045

Claims (20)

[Claims] An electrically excited doctor blade, wherein one sector of a developing roller is brought into physical contact with the surface of an electrically charged doctor blade to hold an electron on the developing roller. A doctor blade for measuring toner for photography, a flexible backing member, a support member for positioning the doctor blade so as to be adjacent to the developing roller, and a side of the support member facing the developing roller. And about 0.5 to about 31.0 inches (deflection) / inch (length) of the flexible foam layer bonded to the side of the flexible foam layer facing the developer roller. ) / Pound (force) rigid shim and a solid binder provided on said flexible backing member, wherein the conductive means and the grit particles are completely dispersed. And a layer containing
The flexible backing member, the conductive means, and the layer having a grit may be bound to the support member and bend so as to extend below the foam layer and the shim. A doctor blade comprising contacting said layer with conductive means with said sector of said developing roller in operation. 2. The doctor blade according to claim 1, wherein said conductive means is a conductive filler dispersed in said binder layer carried on said flexible backing member. 3. The doctor blade according to claim 2, wherein the shim is fixed to a front edge of the foam layer and extends over the entire length of the foam layer. 4. The doctor blade of claim 3, wherein the stiffness of the shim is greater than the stiffness of 0.014 inch thick polyester and less than or equal to the stiffness of 0.012 inch thick stainless steel. 5. The doctor blade of claim 4, wherein the shim is formed from a material selected from the group consisting of brass, polyester, stainless steel, phosphor bronze, beryllium copper, and polycarbonate. 6. The grit according to claim 6, wherein said grit has a diameter of about 8 to about 20.
6. The doctor blade of claim 5, comprising micron sized particles. 7. The grit according to claim 6, wherein the grit comprises particles sized at 13 to about 16 microns in diameter.
The doctor blade according to 1. 8. The doctor blade according to claim 7, wherein the grit is a ceramic oxide. 9. The doctor blade of claim 8, wherein the amount of conductive particles used provides the binder grit layer with an electrical resistance of less than about 2 × 10 5 ohms / cm 2. 10. The doctor blade according to claim 9, wherein the conductive particles are carbon black. 11. The shim substantially covers a surface of the foam layer facing the developing roller.
The doctor blade according to 0. 12. The doctor blade according to claim 11, wherein the shim is fixed to the foam layer by an acrylic adhesive. 13. The doctor blade according to claim 12, wherein the shim is formed from stainless steel. 14. The doctor blade of claim 13, wherein said shim is about 0.005 inches thick. 15. The doctor blade according to claim 12, wherein the shim is formed from polyester. 16. The doctor blade of claim 15, wherein said shim is about 0.014 inches thick. 17. The support member extends from a body of the support member such that the flexible backing member and the layer comprising grit and conductive filler are substantially directly oriented in the sector direction. Including an extension that terminates at a location,
The doctor blade according to claim 10. 18. The doctor blade according to claim 5, wherein the shim is fixed to the foam layer by an acrylic adhesive. 19. The doctor blade according to claim 18, wherein the shim is formed from polyester. 20. The doctor blade of claim 19, wherein said shim is about 0.014 thick.